The hostname is not editable because the default policy has

        <action id="org.freedesktop.hostname1.set-hostname">
                <description>Set host name</description>
                <description xml:lang="pl">Ustawienie nazwy komputera</description>
                <message>Authentication is required to set the local host name.</message>
                <message xml:lang="pl">Wymagane jest uwierzytelnienie, aby ustawić nazwę lokalnego komputera.</message>
                <defaults>
                        <allow_any>auth_admin_keep</allow_any>
                        <allow_inactive>auth_admin_keep</allow_inactive>
                        <allow_active>auth_admin_keep</allow_active>
                </defaults>
        </action>

And gnome-control-center doesn't make the field editable unless the polkit response is 'yes'. Possible solutions:

- add a way to bring up the polkit auth dialog when the reply from polkit is 'maybe'

- override the default policy by installing a rules file that sets allow_active to 'yes'

Can we make it a "yes" for admins in active sessions?

It is possible to write a rule that does that, pretty sure.

http://www.freedesktop.org/software/polkit/docs/latest/polkit.8.html#polkit-rules

has instructive examples

That would make a reasonable default I think.

<hadess> fredp, another one for 3.6 blockers: https://bugzilla.gnome.org/show_bug.cgi?id=679281

Here's a rule that works:

polkit.addRule(function(action, subject) {
        if (action.id == "org.freedesktop.hostname1.set-static-hostname" &&
            subject.local &&
            subject.active &&
            subject.isInGroup ("wheel")) {
                return polkit.Result.YES;
        }
});

Put this in a file called gnome-control-center.rules, and install it in /usr/share/polkit-1/rules.d/

commit 4d62e05fb088d64c3133912f0995a42157b8e968
Author: Matthias Clasen <mclasen@redhat.com>
Date:   Wed Aug 22 14:15:04 2012 +0100

    common: Add Policykit rules for hostname setting
    
    Allow setting the computer's pretty hostname if the user is an admin.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=679281

*** Bug 676979 has been marked as a duplicate of this bug. ***